Articulators have commonly been employed in the prior dental art as a gnathological setup technique for positioning maxillary (upper) and mandibular (lower) arch models in movable relation to each other between an occluded position and a position defining a centric wedge of opening corresponding to the wedge opening of a patient.
Most of the prior art setup techniques only require that one find centric occlusion by grinding a set of arch models on a model grinder while the teeth are fitted together with the teeth on the mandibular arch model being cut off and set up in wax. Some techniques set up half of the arch at a time in an effort to maintain the vertical height while others only remove some of the teeth from the arch. Usually the mandibular arch model is completed and then the maxillary teeth are removed from its arch model and set to occlude with the mandibular model set up using a well known table top orientation technique to establish the arch relation between the two models. When the setup is completed, the models are fixed in the articulator to create an arc opening similar to that of the patient. A positioner or other dental device may then be used based upon the setup and mounting achieved in the articulator.
Various other prior art techniques are available over and above the simple approach described above. However, all of the known prior art techniques have inherent limitations when transferring the centric wedge opening of the patient to the set of arch models mounted on the articulator.
One of these prior art methods accomplishes orientation of the mandibular arch model on the articulator by measuring the angle of the mandible from the condyles to the tip of the incisors, the angle taken from a two-dimensional head plate which superimposes both the condyles as well as the lower incisors and molars. The two-dimentional basis of the head plate makes it difficult and unlikely to accurately capture the three-dimensional position of the plane of occlusion for the models relative to the condyles and the mandibular hinge axis definded by the condyles. The method described immediately hereinabove does not find an accurate relationship of the maxillary to the cranial base or the mandibular relation to the maxillar. Similarly, this technique does not establish the centric wedge of opening corresponding to that of the patient with the condyles being seated in the superior position within the fossae. A gnathological positioner produced using this prior art method and used by the patient for an extended period of time causes the patient to subluxate the condyles and extend them forwardly in order to seat his teeth in the gnathological positioner. This condition may cause temporomandibular joint (TMJ) problems, such as pain, dysfunction, adverse tooth movement and trauma, centric slides, and a breakdown of the periodontal membranes.
Accordingly, there has been found to remain a particular need for a method and apparatus for accurately positioning the maxillary and mandibular arch models in the articulator with the plane of occlusion mounted relative to the axes of the articulator in three dimensional simulation of the same intraoral relationship for the patient.